There are two types of battery monitors, shunt-based and voltage-based.
The most simple type is the voltage-based monitor and frequently comes standard on most mobile power applications. This type of monitor just measures the real-time voltage of the battery and uses it to estimate its state of charge.
Voltage-based monitors are used to monitor Lead Acid Batteries as you measure these by their voltage.
Shunt-based Monitors are used to monitor Lithium Batteries as you have to measure these by capacity not voltage.
The shunt-type monitor is much more accurate because it measures the actual energy flowing into and out of the battery. These battery monitors require a shunt to be installed on the negative side of the battery terminal. The shunt measures the real-time voltage of your battery system as well as the current draw.
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